EP0508130A1

EP0508130A1 - Servocontrolled axis manipulator with programmable spraying heads

Info

Publication number: EP0508130A1
Application number: EP92104087A
Authority: EP
Inventors: Danizzo Taccon; Gloriano Taccon
Original assignee: Taccon Costruzioni Mecaniche Sdf Di Agironi & C
Current assignee: Taccon Costruzioni Mecaniche Sdf Di Agironi & C
Priority date: 1991-03-12
Filing date: 1992-03-10
Publication date: 1992-10-14
Also published as: US5266115A

Abstract

A manipulator with servocontrolled axes (10, 11, 12), comprising two or more programmable spraying heads (14) for spraying various liquids and/or air into moulds, more particularly foundry moulds. The manipulator comprises one or more servocontrolled axes (10, 11, 12), controlled by a programmable logic (CPU) to move two or more spraying heads (14) in a continuous or discontinuous mode along a predetermined path. The heads (14) are designed to spray, in a programmed manner, various liquids which are atomised under pressure or by a strong jet of compressed air, thus performing the dual action of atomiser and air blower.

Description

The present invention relates to a manipulator having one or more servocontrolled axes, with spraying heads suitably made to spray, in a programmable manner, various liquids which are suitably atomised under pressure or by a controlled jet of pressurised air which enables each head to perform the dual function of atomiser and air blower.
In the field of foundries, and die molding in general, there is the need to spray different treatment liquids, for example lubricating or releasing agents, or compressed air inside a mould, for the routine operations of cleaning and preparing the moulds.
Given the complex configuration and structure of the moulds, more particularly in the field of foundries, manual sprayers are at present used on each occasion, actuated by the relevant operator.
Likewise known are multiaxis actuators in general, nevertheless their use in foundry production processes and in die molding in general, for cleaning and preparing moulds, is somewhat difficult and onerous, due to the extremely bulky structure of the manipulator, unsuitable for allowing the insertion of the spraying heads between an open mould of complex shape and configuration.
At present servocontrolled axis manipulators with programmable spraying heads are not known, and which are moreover simple in structure, inexpensive and extreme versatility of use, having furthermore the possibility of adjusting the quantities of liquid sprayed.
The object of the present invention is to provide a manipulator with one or more servocontrolled axes and with programmable spraying heads, suitable for fulfilling the needs referred to above.
A further object of the present invention is to provide a manipulator, as related above, fitted with one or more spraying heads designed to perform a dual function of atomiser and air blower and which are suitably adjustable and tiltable in a fully independent manner, in order to spray liquids and to blow air into whatsoever point or direction required.
A further object of the present invention is to provide a manipulator, as related above, provided with servocontrolled spraying heads which also have the possibility of adjusting the quantity of liquid sprayed.
These and other objects are achieved by means of a servocontrolled axis manipulator, with programmable spraying heads, according to the characteristic features of the main claim.
The manipulator with programmable spraying heads, according to the present invention, will be illustrated in greater detail hereinbelow, with reference to the figures in the accompanying drawings in which:

Fig. 1 is a perspective view of a three-axis manipulator;
Fig. 2 is a top view, of the manipulator of Fig. 1;
Fig. 3 is an enlarged sectional view along line 3-3 of Fig. 2;
Fig. 4 is an enlarged sectional view along line 4-4 of Fig. 3;
Fig. 5 shows a front view of a distributor with two adjustable spraying heads, according to a further characteristic feature of the invention;
Fig. 6 shows a view from above of Fig. 5;
Fig. 7 is an enlarged detail of an articulated conduit for feeding a spraying head according to the previous figures 5 and 6;
Fig. 8 is an enlarged section of a spraying head according to the invention;
Fig. 9 is a general diagram of the control and fluid feed apparatus for the manipulator in Fig. 1.

With reference to Figures 1 to 4, we will describe hereinbelow the general characteristic features of a manipulator with three servocontrolled sliding axes, for the programmed movement of two spraying heads; nevertheless it is understood that a manipulator according to the invention could have any number of sliding and/or rotational axes, positioned differently in order to move or position the heads according to whatsoever path required, which can be obtained, in a programmed manner, by means of linear and/or circular interpolation, in whatsoever plane and/or in space, by means of a suitable programming unit.
The example in Fig. 1 shows a three-axis manipulator, whereby two spraying heads can be moved in the directions defined by three orthogonal axes, as represented schematically. Nevertheless the manipulator can be accomplished with one or more axes according to uses and necessities.
More precisely the manipulator comprises a first horizontal axis 10, also referred to as the longitudinal axis, a second horizontal axis 11 , also referred to as the transverse axis, slidingly supported by the previous axis and a third vertical axis 12 slidingly supported by the transverse axis 11 referred to above. Finally 13 in Figure 1 denotes an arm sliding along the vertical axis to support two spraying heads 14 suitably attached to the arm in a pre-positioned or variously adjustable manner, as will be explained hereinunder.
As shown in the figures, the first axis 10, or longitudinal axis, consists of a tubular metal section 15, having a plurality of longitudinal slots 16 for assembling the various components. The use of slotted tubular sections for accomplishing manipulator axes is found to be extremely advantageous since it not only allows easy and rapid assembly of the various components, but it substantially reduces the weight of the moving parts of the manipulator.
Fixed on the two sides of the section, at respective longitudinal slots 16, are two metal bars or prismatic guideways 17, along which a carriage 18 slides, supporting the transverse axis 11. The carriage 18 is provided with sliding blocks 19, and is moved by means of a screw-nut screw drive system, comprising a screw 20, actuated by a direct current motor 21, shown in the diagram in Fig. 9, and a ball lead nut or nut screw 22 carried centrally by the carriage 18.
Similarly, the second horizontal axis 11 consists of a tubular section 23, identical or similar to the previous one, attached to the carriage 18 by means of clamps 24, which enable the longitudinal position of the section 23 to be adjusted in relation to the carriage 18. This is shown in the detail of Fig. 4 where it can be seen that each clamp 24 has a projecting part which engages in a lateral slot 16 of the section 23, said clamp 24 being attached to the surface 18 of the carriage by means of a screw 25.
Correspondingly, the second axis 11 comprises two prismatic guideways 26 attached to two lateral slots 16 for the sliding of a second carriage 27 provided with sliding blocks 28.
In a similar way to the first axis 10, the carriage 27 of the second axis is moved longitudinally by means of a ball screw-nut screw drive system 29, 31 actuated by a respective direct current motor 30.
The third axis or vertical axis 12 is in turn attached, for example by means of an intermediate section 32, to the carriage 27 of the second axis in order to be mobile with it. In this case too the vertical axis 12 consists of a tubular metal section 33 with longitudinal slots 16 for attaching the various components. More particularly, as shown in Fig. 1, in order to reduce the overall dimensions of this third axis as much as possible, the horizontal arm 13 supporting the spraying heads 14, is attached to a carriage 34 guided along the axis 12 by a single prismatic guideway 35, as well as by a screw 36 driven by its own direct current motor 37. The screw 36 in turn engages with a ball nut screw 38 carried by the carriage 34 on the opposite side to the prismatic guideway 35.
From what has been said so far it is clear that, by accomplishing each axis of the manipulator by means of a tubular metal section provided with prismatic guideways for the sliding of a carriage, attached to the section along corresponding longitudinal slots, with which the metal section is provided, not only allows the positioning of the various components to be adjusted, but also an extremely simplified and economic construction of each axis, at the same time maintaining high working flexibility and reliability of the entire manipulator. Furthermore, since the spraying heads 14 are carried by an arm with extremely small overall dimensions, which projects cantilevered from the carriage of the vertical axis, it is clear that in this way the spraying heads 14 can be inserted between the opposite surfaces of an open mould, choosing the most appropriate direction for insertion according to the structural complexity of the mould and the positioning in relation to the latter by the manipulator.
The solution of figures 1 and 2 enables the arm with the spraying heads 14 to be inserted either laterally or from above or the upper part of a die-casting machine.
Moreover, in the solution shown in Figures 1 and 2 the two axes 11 and 12 enable movement along both rectilinear and curved paths, achieved either through linear interpolation of the two movements, by circular interpolation or a combination thereof, controlled by a suitable logic unit. The third axis 10, in the case shown, is used to move in space. In combination with or in place of one of the axes 10, 11 and 12 a rotational axis could also be used, placing a rotary table, driven to rotate continuously or reciprocally by a motor, on a suitable structure or on one of the carriages.
Figures 1 and 2 represent schematically two opposite spraying heads 14, attached to a transverse section of the support arm 13, without any possibility of relative positioning. Nevertheless it is preferable that the spraying heads 14 be adjustable in relation to the support arm in order to adapt to the various requirements of use.
The heads 14 could be supported and positioned by whatsoever suitable means, nevertheless Figures 5 to 7 show a preferential solution which makes use of special articulated conduits which allow both feeding of fluids to the heads 14 and positioning of the same heads.
The use of articulated conduits is shown in Figures 5 to 7, for two heads 14 fed with one or more fluids and with compressed air, by means of a distributor 40 having a conduit 41 for feeding compressed air which is used for the aspiration and atomisation of a liquid fed to the heads 14 by the distributor 40, by means of a second conduit 42.
The conduits 41 and 42 of the distributor are connected to the respective inlets of air and liquid of each head 14, as explained hereinbelow, via a fitting element 43, 44 and via respective articulated conduits 45 and 46 which, as shown in Fig. 7, also define various orthogonal axes of positioning in space for each head 14.
In the case shown in Figures 5 and 6, the two fittings 43 and 44 are used to feed compressed air and a treatment liquid to two opposite heads 14, nevertheless it is clear that the distributor 40 could be provided to feed also more than two heads according to the requirements of use of the manipulator.
Figures 5 and 6 of the drawings show a front view from above of the articulated conduits for feeding and positioning the heads, while Figure 7 shows a view lying in a plane of one of said conduits, in order to clarify its characteristic features and the relative position of the various articulation axes.
Each feed conduit, for example the conduit 45, is formed by several tubular sections variously articulated and positioned one with respect to the other.
More particularly, as shown in Figure 7, each articulated conduit 45 and 46 comprises a first tubular section 47 screwed into a first inlet of the head 14 and respectively to an intermediate joint 48. The articulated conduit 45 moreover comprises a second tubular section 49, orthogonal to the previous one, defining a first axis of relative rotation between the joint 48 and a further intermediate joint 50; the latter is connected in turn to a third joint 51 via a further tubular section 52 defining a second rotational axis orthogonal to the previous one. The joint 51 is connected in turn to a joint 53 by means of an intermediate tubular section 54 screwed to the above joints and arranged parallel to the first rotational axis 49. The joint 53 is connected in turn to a further joint 55 via a further tubular section 56 defining a third rotational axis parallel and coplanar to the second rotational axis 52. The joint 55 is connected to a further joint 57 via an intermediate screwed tubular section 58, and the latter joint 57 is finally connected to the distributor 40, via a final tubular section 59 defining a fourth rotational axis parallel to axes 52 and 56. The second articulated conduit 46, connected to the other inlet of the head 14, is formed identically to the articulated conduit 45. In this way each head 14 is supported by means of a complex of 90° articulations which allow the head to be positioned angularly both in a vertical and/or in a horizontal plane. The number and arrangement of the rotational axes of the articulations could also be different from what is shown.
Each head may be locked in whatsoever angular position as shown by the dotted lines in Figures 5 and 6, preventing rotation of the respective articulation axes. In this respect, each tubular section defining a rotational axis is composed of a tubular element 52, one extremity of which screws into a joint while the other is free to rotate in the other joint, providing a suitable toroidal seal or O-ring 60. The tubular element 52 is locked in the required angular position by means of a ring nut 61 which screws onto a threaded portion 62 of the relative joint, locking a flange 63 of the tubular element against the threaded extremity of the joint element. In this way, by loosening the individual ring nuts of the various articulation axes of the two pipes 45 and 46, it is possible to position each head 14 vertically and horizontally and lock it into position by rescrewing once again the ring nuts 61.
The spraying heads 14 may be of whatsoever suitable type, for example of the type with high pressure liquid atomisation or, according to another aspect of the invention, of the type shown in Figure 8 in which each spraying head 14 aspirates the liquid, by means of the vacuum created by a flow of compressed air, and comprises an air-actuated control valve so as to act both as a liquid atomiser and an air blower.
In this respect each spraying head 14 comprises a body 63 having a suction chamber 64 provided with a spraying nozzle 65 screwed into the chamber itself. The suction chamber 64 is directly connected to a first inlet 66 for the compressed air which opens into the chamber 64 through a convergent conduit or inyect nozzle 67, partially projecting into the chamber in line with the bore 68 of the nozzle 65.
The spraying head 14 comprises a second inlet 69 for the liquid to be sprayed, leading into a convergent passage 70 which opens into the chamber 64 orthogonal to and at a short distance from the nozzle 67 which feeds the air under pressure.
The conduit 70 extends at the rear in the body 63 of the spraying head, with a cylindrical section for housing a servocontrolled control valve, denoted as a whole by 71, actuated by the same air under pressure, as explained hereinbelow.
The control valve 71 substantially comprises a closing member 72 provided with an O-ring 72', said member 72 being movable longitudinally in a sleeve 73 which can be screwed in the cylindrical portion of the conduit 70. Seals 74 enable the necessary tightness while a first counter spring 75 enables the position of the sleeve 73, and hence the flow of the liquid, to be adjusted, closing to a greater or lesser extent with its internal extremity the passage of the liquid from the inlet 69.
The closing member 72 is normally returned into an open condition of the valve by a second spring 76 which on one sides rests against an annular shoulder inside the sleeve 73, while on the other side it rests against a piston member 77 sliding in the cylindrical chamber 78 formed in the rear cylindrical portion of the sleeve 73, coaxially to an inlet 79 for the air under pressure.
It is clear therefore from Figure 8 that in the condition shown, in which the valve 71 is open, the feeding of air under pressure through the inlet 66 generates a vacuum in the chamber 64 which creates a suction of the liquid through the inlet 69 which, through the pipe 70 of the valve, enters the chamber 64 and in this way is sprayed in an atomised form through of the nozzle 65.
A head designed in this way is therefore able to function by exploiting the known Venturi effect to create the necessary vacuum for sucking the liquid, in a totally controlled manner, by the valve 71 which allows the performance of the two functions of atomiser of the liquid for treating the mould and of air blower. It is thus clear that by feeding air under pressure to the valve 71, through its inlet 79, the piston 77, overcoming the reaction of the spring 76, acts to move the closing member 72 forwards until the conical conduit 70 is closed tight. In this way the entry of the liquid is prevented and the nozzle 65 of the head is only fed with compressed air.
With reference to Figure 9 we will describe finally a general diagram of programmable control apparatus of the manipulator and spraying heads according to the invention.
As can be seen from this figure, each motor 21, 30 and 37 for driving the three axes of the manipulator is connected to an electrical feeder 80 controlled by a CPU which can be programmed by means of a programming keyboard 81. The keyboard 81 is for example of portable type with a liquid crystal monitor on which a guided menu appears, which can be selected by means of the function keys of the keyboard to set all the movements of the manipulator according to the path which the spraying heads have to follow in order to enter and exit a mould. Each drive motor 21 is provided with a signal generator or encoder 21', 31', and 37' which send respective control signals to the CPU corresponding to the positions of the carriages 18, 27 and 34 respectively.
It can be seen moreover from Figure 9 that the inlets 66 and 79 for the compressed air are connected to a source of air under pressure 82 through respective servovalves 83, 84 actuated by the feeder 80 under the control of the CPU. Finally, in the same figure, it can be seen that the inlet 69 for the liquid can be connected to one or more sources of liquid 85, 86 via one or more servovalves 87, again actuated by the feeder 80 under the control of the CPU. It is therefore clear that, as a function of the working program already stored in the memory and the program of the path which can be stored each time in the logic control unit, not only is it possible to program the sequences of the positions which the various carriages of the three axes will assume continuously or by steps, but it is also possible to control in a programmed manner the sequence of operations of spraying the treatment and cleaning liquid or liquids, by means of air under pressure, in the two levels of a mould, by means of a servocontrolled manipulator which is extremely practical and versatile to use and which combines these characteristic features with an extremely simple construction and economical use.

Claims

Servocontrolled axis manipulator having spraying heads (14) for at least one treatment liquid and for feeding air under pressure, characterised in that each axis (10, 11, 12) of the manipulator comprises a tubular section (15, 23, 33) having longitudinal slots (16) for assembling component parts, at least one prismatic guideway (17, 26, 35) attached to one of the slots (16) for the sliding of a relative carriage (18, 27, 34) , a screw-nut screw transmission (20, 22; 29, 31; 36, 38) for driving the carriage, said screw-nut trasmission being connected to a respective drive motor (21, 30, 37), said screw and said drive motor being attached to a longitudinal slot (16) of the abovementioned tubular section (15, 23, 33), each spraying head (14) being connected to at least one source (85, 86) of treatment liquid via a respective servovalve (87), and a programmable logic control unit (CPU) being also provided, said control unit being operatively connected to said servovalve (87), respectively to said drive motor (21, 30; 37), and means (21', 30', 37') for detecting the position of the carriages (18, 27, 34) along said axes (10, 11, 12), and to control the movement of anheads supporting arm (13) along a programmed path.
Manipulator according to claim 1, characterised in that said means for detecting the position of the carriages comprise a signal generator (21', 30', 37') connected to the drive motor (21, 30, 37).
Manipulator according to claim 1, characterised in that said means for detecting the position of the carriages (18, 27, 37) comprises a step motor operatively connected to the logic control unit (CPU).
Manipulator according to claim 1, characterised in that the inlet (69) for the liquid of the spraying head (14) can be connected to one or more sources (85, 86) of liquids via respective servovalves (87) controlled by the logic control unit (CPU).
Actuator according to claim 1, characterised in that each head (14) is attached to a support arm (13) sliding along an axis of said actuator, by articulated conduits (45, 46) enabling different angular positions of the head (14).
Actuator according to claim 5, characterised in that at least a first and second adjustable heads (14) are connected by articulated conduits (45, 46) to a common fluid distributor (40) attached to the mobile arm (13) of the actuator.
Actuator according to one or more previous claims, characterised in that each articulated conduit (45, 46) for feeding compressed air, and respectively a liquid for each spraying head (14), comprises tubular sections, articulated one to the other, said tubular sections being angularly adjustable on two or more rotational axes arranged parallel and/or orthogonal one to the other.
Actuator according to claim 7, characterised in that each rotational axis of the articulated conduits (45, 46) comprises locking means (61) for locking rotation.
Actuator according to any one of the previous claims, characterised in that said spraying head (14) comprises a body (63) and an suction chamber (64) having a spraying nozzle (65); a first inlet (66) for air under pressure having an injector nozzle (67) extending into said suction chamber (64) coaxially to the abovementioned spraying nozzle (65), as well as a second inlet (69) for a liquid comprising a conduit (70) opening into said suction chamber (64), orthogonal to and in the vicinity of the air injector nozzle (67); the spraying head (14) moreover comprising a control valve 71 in said conduit (70) and drive means (77, 78) for actuating said control valve (71) between closed and open conditions of the liquid inlet (69) mentioned above.
Actuator according to claim 9, characterised in that said control valve (71) comprises a closing member (72) axially moving in a sleeve (73), said sleeve (73) being screwed and adjustable in said conduit (70) for the liquid, and pneumatically actuated drive means comprising a piston member (77) movable in said sleeve, said piston member (77) being connected to said closing member (72) and spring means (76) for actuating the closing member (72) of said control valve (71) between the closed and open condition respectively, and manually adjustable flow control means comprising said sleeve member (73).